Electromagnetic core construction



May 9, 1950 l. K. FOG

ELECTROMAGNETIC CORE consmucnon Filed Oct. 17, 1945 FIG. I.

3 FIG. 5..

INVEN TOR VAR K. Foe avwfi AT TOR NEY Patented May 9, 1950 2,50%637 ELECTROMAGNETIC! CORE CONSTRUCTION Ivar K. Fog, King, Ontario, Canada, assignor to Wagner Electric Corporation, St. Louis, Mo., a corporation of Delaware Application'October 11, 1945, Serial No. 622,748

In Canada April 28, 1945 1 Claim. i

This invention relates to improvements in the means for securing the sheet metal stamping-s of electro-magnetic cores and the principal objects of the invention are to obtain the secure fastening of the sheet metal stampings in a unitary core mass so that the stamped sheets will not be buckled or forced out of shape and uniform contact of the surfaces of the stampings will be maintained.

A further object is to devise a very simple and effective means for securely fastening the core laminatlons which may be applied with great ease and rapidity and to provide a fastening means which will assist materially in reducing vibration of the laminations and which will maintain the security of the fastening 0f the laminations indefinitely.

The principal feature of the invention consists in the insertion of mating wedge members into aligned orifices extending through the laminations of a core structure effecting an outward pressure against the edges of the holes in the laminations through the forcible contact of wedges of resilient material.

In the accompanying drawings Figure 1 is a plan view of a portion of a laminated core for an electro-magnetic machine.

Figure 2 is a sectional view through the core shown in Figure i taken on the line 2-2 and showing the wedge means for securing the lami nations together.

Figure 3 is an exaggerated sectional view through a plurality of laminations showing the securing wedges being inserted therein.

Figure 4 is a view similar to Figure 3 showing the two wedge elements of a fastening member secured in place.

Figure 5 is a, perspective detail of a pair of fastening wedges.

Figure 6 is a very much exaggerated sectional detail view of portions of laminated plates showing the manner in which the fastening wedges form individual gripping means to hold the individual plates.

In the manufacture of electro-magnetic cores; it has been the custom to prepare the stamped be used thereon for engagement with the holding nuts. The use of nuts and bolts had an undesirable feature in the projecting bolt heads and nuts which extend beyond the end laminations.

It has been proposed also to secure the laminations of a core together with rivets but the maintenance of the security of the core depends upon a very small body of metal in the riveted over heads of the metal rivets.

Other means for securing the laminations have been proposed in the form of enclosing casings.

The present invention is extremely simple. merely requires that the laminations be formed with registerin pin holes at a desirable number of points around the circumference of the core and adjacent to the outer perimeter.

The laminations i when stacked together with the pin holes 2 aligned have inserted into such pin holes matched or paired wedge strips 3 which, when the pin holes are round, will be of half-round section. One wedge is inserted into each hole from one side of the core body with the big end resting on a bottom support. The mating wedges are then inserted into each hole from the same side of the core body with the small end first. The small ends of the mating wedges overlap the previously placed wedges within the core structure and they are then driven tightly into place, thus placing the material of which the wedges are formed under compression.

The wedges are preferably made of hardwood, such as birch or maple.

It is well understood by those conversant with the manufacture of sheet metal materials that in punching the metal sheet the punch before it shears the metal depresses the surface, thus forming a rounded or chamfered edge on the upper side of the sheet. The underside, which is of course supported by the die, breaks clear.

It will be readily understood that a structure where a plurality of sheets are placed together, as in a magnetic core, the surface of each sheet will have a chamfered edge around the punched hole into which the fastening members are to he entered. Thus when a plurality of sheets are put together there are a number of minute substantially V-shaped recesses formed between the side. The resulting compression will cause a series of minute bulges to form in the outer perimeter of the first inserted wedges, as illustrated particularly in Figures 4 and 6.

It will be readily understood that when the wedges have been forced into position the material of the wedges first inserted into the holes not moving in relation to the metal sheets while the other members are driven into place, will form ribs entering the V-shaped recesses between the adjacent plates and provide an inter lock between the individual. plates and first in=- serted wedges.

It will be understood that immediately upon the application of the compression pressure the ribs will begin to form on the first inserted wedge, thus preventing the individual metal sheets from being compressed hard together or to bulge down around the edge of the wedge holes and that the outer surfaces of the assembled core will stay flat without irregularity near the holes, thus forming a uniformly shaped core which will be retained securely for an indefinite time. The operation of assembling the core as described will not impose any excessive pressure between the indi vidual sheets and there will be no threading, no riveting and no enclosing casings will be required.

In the process of manufacture the sheets will be stacked to the required thickness, the wedges inserted into position and when driven home the core will be securely and permanently united.

It will be understood that while the wedge pins are herein described as made oi wood, such pins may be made or other materials which will form ribs between the individual sheets when compressed laterally into the crevices which will be formed by the punching or the holes in the sheets. If the wedges are formed or nonmagnetic material no closed circuits will be iormed between the metal sheets and such wedges, consequently there will be less heat losses and a core of higher eficiency will be produced.

Having fully described my invention, that which I claim as novel and desire to secure by Letters Patent of the United States is:

An electro-magnetic core comprising a plurality of metal sheets stacked together and having chainfered holes therethrough aligned to provide a plurality of openings through the core, and pins of non-magnetic resilient material bevelled longitudinally on one side and located in said openings in matched pairs with opposite bevelled faces in pressure engagement, one oi? the pins of each pair having integral ribs on its outer surface individually engaging and interlocking with the chambered edges of said sheets at the holes.

W K. FOG.

REFERENCES (JETEHD The following references are of record in the his of this patent:

UNITED STATES PATENTS Number Name Date 1,320,126 Dudley Oct. 28, 191i 1,654,306 Paszlrowskl Dec. 27, 1927 2,521 Trombetta Nov. 25, 19%

FORElGN PATENTS Number Country Date 2537,23? Germany Aug. 30, 1913 y 

